Method of treating cellulosic materials



Patented Nov. 9, 1931 METHOD OF TREATING caumloslc m'rnnms Denis doGoe'nca and Edmund G. Tarnlner,

assignorstoArnoldPrin North Adams, Mam,

Works, North Adams, Mara, a corporation of Massachusetts No Drawing.Application December 9, 1938,

. Serial No. 101,730

eam. (eta-20y f and wood. The materials to which the process may be mostadvantageously applied are woven fabrics, such as for example cottoncloth, and

more particularly those of rather light weight,-

but the invention is not limited to the treatment of this particularkind of .goods.

The treatment, according to our present invention, includes thepreliminary application of an inactive cellulose solvent to the goods,and the subsequent treatmentof the goods containing such solvent with anactivating agent which enables the solvent to perform its function ofmodifying the character of the goods. Normally inactivecellulosesolvents, capable of being' activated in the manner contemplated by ourpresent invention, are

in general the cuprammonium salts such as obtained by dissolving acupric or cuprous salt in an excess of strong ammonia water..Cuprammonium sulphate, obtained by the action of stron ammonia waterupon copper sulphate, is typical of this class of solvents. Other saltswhich may '26 be employed and which may be produced in an analogousmanner are obtained from the action of strong ammonia water upon achloride, nitrate, cyanide, chlorate, bichromate, formate, acetate,oxalate or citrate of copper. These. and similar 80 salts are thereforeto be understood as normally inactive cellulose solvents for the purposeof the present invention.

The activating agent may be an aqueous solution of alkali metalhydroxide, of'which caustic 8o soda solution is in most respects themost suitable to use.

The effects produced upon the goods in accordance with the presentinvention are quite different from those which occur in the known proc-40 ass or applying an activating agent to thegoods and then passing thegoods containing such activating agent through an inactive cellulosesolvent bath, such as obtained by dissolving cop: per sulphate in anexcess of strong ammonia 45. water. The new eflects are somewhat morenoticeable in lighter weight fabrics than in heavier goods, the hand orthe feel of .the treated fabric becoming wirier and stiller with apeculiar springiness or elasticity which with- 50 stands wear andwashing. The individual threads become semi-translucent, which rendersthe fabric transparent to a remarkable. degree. Regularity of the warpand filling threads, as well as freedomfrom any unevenness due toweaving imperfections, which would show up be- 5 fore the treatment, arequite marked in thefinished goods.

' The effects above described are obtained to a fairly satisfactorydegree by the use of the normally inactive cellulose solvent and theacti- 1o vating agent at ordinary room temperatures, but

a particularly importanttembodiment of the invention comprises thecooling-of the activating agent to temperatures which may be varied fromroom temperature to approximately 32 R, such 5 cooling of the activatingagent resulting in a considerable enhancement or increase in the effect.with reference to the cooling of the activating agent, it isto be notedthat the reaction between the cuprammonium salts and go the hydroxidesof alkali metals is exothermic in nature, so that the continuousmovement of a fabric containing the cuprammonium salt through a. bathcontaining the hydroxide of an alkali metal would tend to raise thetemperature of the alkali metal hydroxide bath and increase the loss ofammonia fromthe cuprammonium salt solution carried by the fabric. Thecooling of this bath and the maintenance of temperatures below roomtemperature reduces the tend- 3o ency of the ammonia to be driven off.

For the purposes of clearly illustrating the principl'es of theinvention, we may refer to the treat merit of thin cotton goods withinactive cuprammonium sulphate solution and caustic soda solu- 35 tion.For the production of the cuprammonium salt solution we may dissolve,for'example, 45 pounds of crystallized copper sulphate in 10 gallons ofwater. and slowly mix 8 gallons of 29% commercial aqua ammonia into thesolution to 40 make- 25 gallons of copper ammonia salt solution. Thecaustic soda solution may be" made, for example, to 50 Twaddell,corresponding to about 29 B. at room temperature. The caustic sodasolution is cooled by immersed cooling coils, v

or other approved. means, to a temperature of, for example, 38 F. Thecuprammonium salt solution may be operated at room temperature. Thecloth is fed under slight tension from a roll, preferably pretentered tofinished width, and passes 0 passes through the caustic soda solution.In I the caustic soda solution, the cloth may dip several times, buttwice is sufllcient, and the cloth is thereafter squeezed out betweenpressure rolls, after which it passes on to the usual lateral stretchingand tentering frame and from there into the souring and washing boxes ortanks.

The strength of the caustic soda solution may, .vary fromabout 15Twaddell up to mercerizing strength of 54 Twaddell and over. The effectis the same in its nature, but the action increases in proportion to thestrength of the caustic solution and inversely with the temperature.

The particular strength of the cuprammonium solution in the above.example is not critical, butv may be taken as typical of good andsatisfactory commercial operation. Inactive cellulose solvent solutions,employing any of the other copper salts previously referred to, may bemade up in an analogous manner to have equivalent copper'con tentthough, as stated, the particular strength of solution is not at allcritical.

y In the above example reference has been made to the padding of thegoods with the cuprammo nium solution, and the subsequent immersion ofthe goods in the caustic soda solution. The speed of travel of the clothmaybe such as to represent, for example, 3 to '8 seconds treatment ineach of the solvent and solvent-activating baths. It is desirable topromptly deliver the padded cloth into the caustic soda bath to minimizethe escape of ammonia after the initial padding.

Instead of applying the inactive solvent to the goods and treating thepadded goods in the manner described, we may apply these reagents to thegoods in other ways, as by spraying, transfer rolls, and the like. Theeifect upon the goods is indeed such that it offers particularadvantages as a printing process, and. may be employed to producedesigns and figures due to the marked difference in appearance betweenthe treated and untreated portions of the goods. For this purpose thegoods may, for example, first be printed with a plain or colored resistand then subieeted to the cuprammonium salt bath and caustic alkalibath. A still further important feature of the action of thecuprammoniumsalt solution and the caustic alkali solution upon the goodsis the marked effect which it has on the. action of dyes and printingpastes applied to the treated 1 goods. After the treated goods have beensoured 'of printing and dyeing operations.

and washed, subsequent dyeing or over-printing produces deeper shades onthe treated parts than on untreated parts of the goods. Thus a greatvariety of effects can be obtained by the use of the treatment inconjunction with various, types Quite complex effects maybe obtained,for instance,.by printing the cloth with a resist-or resists, eitherwhite or colored, and in the same operation applying suitable'color orcolors in a fitted pattern, after which the goods are run through thecuprammonium salt and caustic soda treatments described. The effects canbe varied by placing the resist roller ahead of or after the otherpattern rollers, or'out oi register, so that the color pattern isprintedpartly over the resist and hence washes out more or less to producehalf-tone effects during the subsequent cuprammonitim salt and causticsoda treatment. Any print color can be used for printing before thecuprammonium salt and caustic soda treatments, provided the color befairly fast to caustic and copper solutions of such concentrations asmentioned, and also fast to such acid as encountered in the subsequentsouring. The resist employed in any of the operations described my beselected at the discretion of the operator, egg albumen. casein andcellulose acetate being suitable examples.

We claim,:---

1. A method of treating cellulosic material which comprises applying tothe material a normally inactive cellulose solvent composed essentiallyof a cuprammonium salt in aqueous amw monia and thereafter treating thematerial containing such solvent with a solvent activating agent.

2. A method of treating cellulosic material which comprises applying tothe material it normally inactive cellulose solvent composed essentiallyof a cuprammonium salt in aqueous am- 4. A method of treating:cellulosic material which comprises applying to the material a solutioncomposed essentially of aqueous ammonia and cuprammonium treating thefabric containing such solution with an alkali metal hydroxide solutionat a temperature in the neighborhood of 38 F4, said firstmentionedsolution normally incapable of dissolving cellulose but acquiringcellulose solvent propertiesin the presence. of the alkali metalhydroxide.

sulphate and thereafter 5. A method of processing woven fabrics ofcellulosic material which comprises printing a resist and a color inmatched patterns upon the fabric, thereafter applying to the resistedand color printed fabric a normally inactive cellulose solvent composedessentially of a solution of cuprammonium salt and aqueous ammonia,thereafter treating the fabric containing such solvent with a solventactivating agent, and subsequentiy souring and washing.

6. A method of treating cellulosic material which comprises applying tothe material a solution normally incapable of dissolving cellulose andcomposed essentially of a cuprammonitim salt and aqueous ammonia andthereafter treating the material containing the salt with an alkalimetal hydroxide, to render the solution active-as a cellulose solvent. I

7. A method of treating cellulosic material which comprises applying tothe material a solu tion normally incapable of dissolving cellulose and.compos'ed'essentially of a cuprammoniumf salt and aqueous ammonia andthereafter treating the material containingthe salt with an alkali metalhydroxide at a; temperature below room temperature, to renderthesolutionactive as a cellulose solvent.

8. A method of processing woven fabrics of oellulosic material whichcomprises applying to the goods a solution composed essentially of acuprammonium salt and aqueous ammonia, incapable oi dissolving cellulosewhen notactivated A by alkali metal hydroxide, then applying to thesolution remaining in the goods an alkali metal hydroxide to activatethe solution, the action of the activated solution upon the goods beingconfined to limited areas to create a pattern or design, souring andwashing the goods, and thereafter dyeing or over-printing with a. dye.

DENIS m: GOENCZ. EDMUND C. TARNUZZER.

